Re SB 102

[Bob, WB2UJD]

Stan,

Check the IF xtal oscillator frequencies with a counter.  I forget where I
tapped onto, probably on the end of C8 away from V16 pin 7.  You will
probably find the USB xtal is off freq.  Otherwise, the IF filter passband is
off.  This would again be due to an xtal  which hads drifted, but inside the
filter (which is an array of xtals).

As for the S-meter, I don't know much about it's function in xmit, but
problems with the meter in the S meter position are almost always related to
R107 (100K) drifting high.  R106 may be a problem as well (and is 22K or 33K,
mine was 33K and the board silk screen showed this as well, but the schematic
shows 22K).  After replacing R107 with a in tolerance resistor, I had to
change R110 to a 330 ohm (again as shown in the schematic), but the board
silk screen showed 510 and that was what was originally installed.  After
that, I got good S meter readings.

For what it's worth, I think the values used in the HW-101 are better (R106
22K, R107 100K, a 10K pot and no R110), never had a bit of problem with the S
meter in that rig.  I have thought of going to that arrangement, and think it
works the best based on my experience, but don't have the higher value
potentiometer in the right style (SB-102 uses 200 ohm pot).  Then again,
maybe it's something else.  Looking at both schematics, the HW doesn't appear
to have R103 and R104 and R105 are slightly different values. R103 looks like
some bias-off when in xmit or such.  Maybe someone else can shed some light
here.  All I know is that the HW S-meter seems to be much better behaved than
my recently repaired SB S meter!

73,

Bob, WB2UJD

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